An outbreak of teat papillomatosis occurred among nulliparous female cattle from autumn of 2004 to spring of 2005 in Hokkaido, Japan. The lesions were macroscopically of the flat-and-round type and in histological analysis proved to be pure epitherial papilloma characterized by epithelial hyperplasia, acanthosis and hyperkeratosis. The etiological agents responsible for this outbreak were identified as bovine papillomaviruses (BPVs) by immunohistochemical and polymerase chain reaction analysis and by electron microscopic observation. From the results of molecular phylogenetic analysis, the BPVs involved in this outbreak were further identified as BPV genotype 6 (78%) and two putative new BPV genotypes (BPV type I: 21%, and II: 21%). Based on an experimental in vivo injection, both BPV types I and II could induce characteristic flat-and-round type papillomas in teats of a heifer. The lesions lasted at least four months. These findings indicate that the two putative new BPVs may have played an important role in this outbreak.
(Research Team for Environmental/Enzootic Diseases, TEL +81-11-851-2132)
